A photovoltaic device converts light energy into electricity. Although the term “solar cell device” may sometimes be used to refer to a device that captures energy from sunlight, the terms “solar cell device” and “photovoltaic device” are interchangeably used in the present application regardless of the light source.
A conventional semiconductor solar cell 100 illustrated in FIG. 1 includes three layers. The first layer 104 is formed by a metal grid on the second layer. The second layer 106 is formed by a semiconductor material on the third layer. The third layer 108, i.e. the bottom or back layer, is a metal blanket layer.
Conventionally, adjacent solar cells are assembled into a solar cell array using interconnect tabs connected to the front and back surfaces of the solar cells. FIGS. 2A-2D depict an exemplary solar cell array 200 where interconnect tabs 206 are used to connect adjacent cells 100 in a serial fashion. The conventional method for assembling solar cells into a solar cell array does not facilitate high-volume assembly of solar cell arrays because connections need to be made to both the back and front surfaces of the solar cells as shown in FIGS. 2A-2D.
FIG. 2A illustrates a cross-sectional view of a conventional solar cell array 200 assembled according to conventional methods. In particular, FIG. 2A illustrates the interconnect tabs 206 contacting the top and bottom surface of adjacent solar cells 100. As shown in FIG. 2A, the interconnect tab 206 is connected to a bottom surface of the back layer 108 of the first conventional solar cell 100 to form a bottom connection 204. The interconnect tab 206 is also connected to a top surface of the semiconductor layer 106 of an adjacent second solar cell 101 to form a top or front connection 202.
A bonding tool performs at least two sweeps across the solar cell array to perform the conventional front connection 202 and the back connection 204 of the solar cells. The first sweep may be across the top or front surface of the semiconductor layer 106 of the solar cell array 200 for forming the front connections 202 illustrated in FIGS. 2A-2D. The second sweep may be across the back or bottom surface of the back metal layer 108 of the solar cell array 200 for forming the back connections 204 illustrated in FIGS. 2A-2D.
FIG. 2B is a top view of the conventional solar cell array illustrated in FIG. 2A. As illustrated in FIG. 2B, the top surface of the first solar cell 100 is connected to the bottom surface of the adjacent second solar cell 101 via the interconnect tab 206. A portion of the interconnect tab 206 is attached to the top surface of the first solar cell 100 to form the top or front connection 202. Another portion of the interconnect tab 206 is attached to the bottom surface of the second adjacent solar cell 101 to form the bottom connection 204.
FIG. 2C is a bottom view of the conventional solar cell array illustrated in FIG. 2A. As illustrated in FIG. 2B, in the conventional method, a tab 208 for a bypass diode connection is provided on the top surface of the semiconductor layer 106 of the conventional solar cell 100. As illustrated in FIG. 2C, one surface of the bypass diode 209 is connected to the back surface of the back metal layer 108 of the conventional same solar cell 100 while the opposite surface of the bypass diode 209 is connected to the aforementioned tab 208.
FIG. 2D is a side view close-up of an exemplary conventional interconnect tab 206 and the bypass diode tab 208 used in connection with the conventional solar cell array illustrated in FIGS. 2A-2C. As illustrated in FIG. 2D, the bypass diode tab 208 effectively wraps around the edge of the solar cell 100 to contact the bypass diode 209 to the top surface and effectively bypasses the solar cell when required.
Accordingly, a new method for assembling adjacent solar cells into a solar cell array is needed that facilitates high-volume assembly of solar cell arrays.